Buffer-spring for printing-presses



J. T. HAWKINS.

BUFFER SPRING FOR PRINTING PRESSE'S.

(No Model.)

Patented Mar. 8, 1885.

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UNITED STATES PATENT flatten.

JOHN T. HAXVKINS, OF TAUNTON, MASSACHUSETTS.

BUFFER-SPRING FOR PRINTING-PRESSES.

SPECIFICATION forming part. of Letters Patent No. 313,205, dated March 3, 1885.

(No model.)

To whom, it may concern:

Be it known that 1, JOHN T. HAWKINS, of Taunton, in the county of Bristol and State of Massachusetts, have invented a new and useful Improvement in Buffer-Springs for Printjug-Presses, which improvement or invention is fully set forth and illustrated in the following specification and accompanying drawings.

The object of this invention is to provide simple and convenient mechanism for operating air-springs whose reactive effort during expansion shall be particularly utilized to a degree equal to the resistance encountered during their compression.

The inventionconsists of the parts or combinations of parts set forth in the claims.

In the accompanying drawings, Figure 1 is a longitudinal vertical section through the center of such parts of a printing-press as are required to illustrate the invention for one end of the press. Fig. 2 is a transverse vertical section at the line X X, Fig. 1, looking to the left, with certain parts omitted not necessary to this figure. Fig. 3 is a vertical longitudinal view, partially in section, of the apparatus complete for both ends of the machine, with the type bed and roller-ways omitted. Fig. 4 is a View in plan of the means of operating the escapevalve when it is required to throw thesprings out of action to enable the operator to turn the machine over the points of reversal without resistance of the springs.

In said figures, the letter A indicates a part of the main frames of the machine; B, an end cross girt or frame,to which the principal parts of the spring apparatus are attached; B, a central cross girt or stay, generally situated immediately under the impression-cylinder, to receive and resist the force of the impression. From B are extended two brackets, B",to which are pivoted two levers, b, formed upon their upper ends into Well-known hook forms to gradually receive without jar the contact of a roller, R, carried in a bracket, R, secured to the underside of the type-bed T. The two levers b are connected by a rod, 1), pivoted to each, the central part of said rod being supported upon a roller, 1', upon the cross-stay B.

In the center and upon the right-hand half of the rod 1) is formed a yoke, b, within which the left-hand part of the rod b slides for a short distance, the end of the lefthand half of rod b within the yoke I) having a nut, b upon it to prevent its withdrawal from yoke b. Two air-chambers, G O, are secured to cross-stays 3. Two plungers, O C, have a good but easy fit in the chambers O O. The plungers O O are made considerably longer in proportion to their respective diameters than is usual in such structures for other purposes. The plungers O O are connected to the levers b by the connecting-rods c, said rods being respectively pivoted to both the plungers G and levers I), as shown.

In the bottom of each plunger 0 is a small clack-valve, V, opening into each air-cham her 0.

The piston I is made air-tight by the usual leather packing, or may be made a sufficientl y tight fit in the chamber 0 to be air-tight.

To the piston P is secured a screw, P, having a stop, P", upon its outer end to limit the maximum compression to be obtained or minimum volume of air-chamber.

P is a hand-wheel secured to a flanged nut, P, working within a guide, P

S is a stop for limiting the motion of the le ver 7) in one direction.

K K are cocks communicating with the airchambers O at the respective inward limits of the strokes of the plungers 0, as at K.

K is a bell-crank lever attached to the plug of one cock K, and K a straightlever secured to the plug of the other cock K.

K" is a rod connecting with the two levers K and K and K is a rod terminating in a handle, K, connected to the other arm of the bell-crank lever K I have found, experimentally, that if the plungers G be made of considerable length in proportion to their diameters, and have each a fair running fit in the chambers O for all pressures required in the chamber of an airspringthey will be practically air-tight, particularly when slightly lubricated. This is particularly true of such springs as used in a printing-press or in similar machines, from thefact that the time within which the compression and expansion of the air is effected is exceedingly small, affording, even in case of a slight leak of air past the plungers C under the high pressures,an exceedingly small chance for a material diminution of pressure from such leak age. To provide, however, that such small loss of air may be restored to the chamber after each compression,a valve, V, is fitted in each plunger 0, allowing, upon the withdrawal of either plunger, such escaped quantity of air to re-enter the chamber and establish equilibrium of pressures within and without before the next compression occurs. The roller R alternately engages the hooked ends of the levers b to alternately compress the air confined in the chambers 0 between the pistons I and the bottoms ofthe plungers G. The function of the rod 1) is to cause either one of the levers b to withdraw the other, and with it its connected plunger O,to the proper point to properly receive the roller It, as limited by the stop S,in case of slight leakage of air past the plungers O. Said plungers from this cause (and from slight cooling of the air in the cham her due to radiation of the heat of compression from its surface) are not restored to that position by the expansive action of the air. The lostmotion of the nut 2) within the yoke 12 is therefore made something less than the whole movement. respectively, of the levers b at the points of attachment of the rod 12.

To vary the accumulations of pressure in the chambers O,the pistons P are moved to or from the bottoms of the plungers O by means of the hand-wheels P and screws P, so as to vary the volumes of the chambers C, and thus increase or diminish at will the maximum pressures obtained. The pistons P being selfpacking and air-tight, no air will escape past them; but if a slight leakage past them should occur during compression it will be restored by the valves V in the same manner as in case of-1eakage past the plungers C. The cocks K, as operated by the levers K K, K, and K and handle K allow the air to escape from beneath the plungers 0 whenever the press may be required to be turned over the points of reversal by hand or run without springs, the handle K being placed for such purpose within easy reach of the feeder or attendant.

I do not confine myself to the exact construction of the several parts herein described, as the whole may be varied to suit the proportions and constructions of the various types of printing-presses to which the general principles above described are applicable.

Having thus fully described my said improvements as of my invention, I claim' 1. In an air-spring apparatus, in combination with a. pair of air chambers or cylinders and plunger-s for compressing the air therein, a yoked rod connected to said plungers by vibrating arms or levers, in the manner substantially as described, whereby the same are operated, substantially as and for the purposes set forth.

2. In an air-spring apparatus, an air chamher or cylinder having an adjustable bottom consisting of a piston, as 1?, provided with a threaded rod passing through a rotary nut fixed in a circular guide, whereby said piston is moved in a right line by the revolution of said nut, substantially as and for the purposes set forth.

' JOHN T. HAWKINS.

\Vitnesses:

ELISHA T. J AoKsoN, HANNAH T. MoNtreoMERY. 

